Philip proved indecisive, soft in nature, and timid. The strong personalities of his parents apparently crushed him, and policies of his father dominated him. People called him "the Bold" on the basis of his abilities in combat and on horseback and not on the basis of his political or personal character. He was pious but not cultivated. He followed the suggestions of others, first of Pierre de La Broce and then of his uncle King Charles I of Naples, Sicily, and Albania.

Philip, proclaimed king, quickly set his uncle, king Charles I of Naples, Sicily, and Albania, on negotiations with Muhammad I al-Mustansir to conclude the crusade with a truce. Charles signed a treaty with the emir, and there was little else to do but return to Sicily. The crusade was postponed until next spring, but a devastating storm off the coast of Sicily dissuaded Philip from any further campaigning. Philip returned to France to claim his throne at the formal coronation of the French monarch at Reims Cathedral on 30 August 1271.

Philip III of France in 1284 responded to the Sicilian Vespers in support of his partially dethroned uncle. With his sons, the king entered Roussillon at the head of a large army on the ultimately unsuccessful Aragonese Crusade. The war took the name "crusade" from its papal sanction; nevertheless, one historian labelled it "perhaps the most unjust, unnecessary and calamitous enterprise ever undertaken by the Capetian monarchy.".[5] On 26 June 1285, Philip III the Bold entrenched himself before Girona in an attempt to besiege the city. Despite the strong resistance, the French took Girona on 7 September 1285.

Philip quickly experienced a reversal, however, as an epidemic of dysentery hit hard the French camp. The disease afflicted king Philip III personally. The French retreated, and the Aragonese enemy handily defeated the French at the Battle of the Col de Panissars on 1 October 1285.

Philip III died of dysentery in Perpignan, the capital of his ally James II of Majorca, on 5 October 1285. His son, Philip IV of France the Fair, succeeded him as king of France. The attempt of Philip to conquer Aragon nearly bankrupted the French monarchy, causing challenges for his successor.[6]

In Divine Comedy, Dante envisions the spirit of Philip outside the gates of Purgatory with a number of other contemporary European rulers. Dante does not name Philip directly, but refers to him as "the small-nosed"[8] and "the father of the Pest of France," a reference to king Philip IV of France.